Inclosed electric fuse.



L. B. BUCHANAN & F. N CONANT.

INCLOSED ELECTRIC FUSE.

APPLICATION FILED JAN 8. 1914.

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Patented Nov. (3, 1917.

In!) en ZOWS UNITED STATES PATENT OFFICE.

LEONARD B. BUCHANAN, OF WOBUBN,

AND FRANKLIN Il'. CON-ANT, OF NEWBUBYPOR'I,

MASSACHUSETTS, ASSIGNORS TO GHASE-SHAWMUT COIIVIPALNY, OF NEWBURYPORT, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

INCLOSED ELECTRIC ruse.

To all whom it may concern:

Be it known that we, LEONARD B. BU- CHANAN and FRANKLIN N. CoNAN'r, citizens of the United States, residing, respectively, at Woburn, in the county of Middlesex, and Newburyport, in the county of Essex, and State of Massachusetts, have invented an Improvement in Inclosed Electric Fuses, of which the following is a specification.

In electric fuses having renewable, fusible elements heretofore made, the means employed for detachably connecting the ends of the fusible-elements with the terminals in some instances have been complicated, requiring the services of a skilled workman to make the connections, and in other instances have been simple, but so con structed as to resemble the ordinary forms of binding-posts and other well-known forms of electric connecting-devices, so much so in fact as to suggest and facilitate the use of substitute forms of fusible-elements other than the fusible elements which are adapted to be employed, which are entirely unsuited to the requirements of the fuse and involve great danger.

The object of this invention is the provision of an improved form of renewable, fusible-element, and of means for detachably connecting the same to the terminals,

both of which are very simple, yet the detachable connecting-means are so construct- 1 ed that an ordinary piece of fuse-wire cannot be employed as a substitute, and furthermore, they are so entirely unlike the ordinary forms of binding-posts and other .Well-known electric connecting-devices as not to suggest the use of any other form of fusible-element than that which it is especially designed and intended shall be employed, and are otherwise desirable.

In accordance with this invention the terminals which are usually arranged at the ends of the fuse for engagement or connection with clips or other means to which the circuit-wires are connected, have ortions arranged inside the fusecase w ich are formed with sockets arranged coaxially 'tudinal axis of the fuse-case, and said soc ets are preferably internally screw-threaded, and which may be composed of a strip of zinc or some equivalent metal, is provided at Specification of Letters Patent.

the fusible-element,

Patented Nov. 6, 1917.

Application filed Janua y '8, 1914. Serial No. 811,058.

said sockets are internally screw-threadedthe threads are preferably made right and left and the plugs correspondingly threaded. Such a-fusible-element, and also such means for detachably connecting it with the terminals maybe easily and cheaply manufactured in quantity but do not lend themselves readily to the employment of substitutes for the fusible-element, as screwthreaded fusible portions of exactly the right size and thread are not readily obtainable. The thread and size should preferably be chosen with this object in mind.

Figure 1 is a side elevation and partial longitudinal vertical section of an inclosed electric-fuse embodying this invention.

Fig. 2 is alongitudinal vertical section of the fuse.

Fig. 3 is a side elevation of one form of fusible-element detached from the fuse.

Fig. 4 is an end view of the fuse.

Fig. 5 is a longitudinal vertical section of one of the terminals.

Fig. 6 is a side elevation of one end-portion of the fuse, the end cap or ferrule being represented by dotted lines.

Fig. 7 is an end view of the fuse shown in Fig. 6.

Fig. 8 is a sectional detail view of a modified form. of connecting means for the detached fusible element.

10 represents the tubular body of the fusecase which is here shown as cylindrical in form; 12,12 are metallic thimbles arran in the open ends of said body.- Each thim ble has a, circumferential outwardly extended flange 13 at its outer end which abuts against the end of said body, and said flange has notches 14 which are extended therethrough longitudinally, two being here shown, which are oppositely disposed, and each notch is arranged opposite one endportion of a long transverse recess 15 formed in'the end of the body, so that the notches, together with their adjacent recesses form bayonet-slots. Said thimbles are secured to the body by pins 16. It is an advantage to form the longitudinal slots or flange 23,

in the end-portions of the case in this manner, but the invention is not limited to thus forming them. 20 represents the metallic end-caps or ferrules which are arranged on the ends of the body, and said caps have inwardly extended pins 21, two being here shown, which are oppositely disposed and arranged to enter the bayonet-slots 14, 15, upon a longitudinal and subsequent rotary movement of the caps, thereby to detachably connect the caps with the body. In cases where the fusible-element is made detachable it is desirable that the end-caps also shall be detachable, but the invention is not limited to the precise means here shown for detachably connecting the end-caps with the body. Each end-cap as here shown, has a large center-opening 22 at its end, thereby leaving an inwardlyextended marginal lip and at the outer end of each thimbletwo circular plates 25, 26, are arranged which are coextensive with the end 7 of the body and serve to substantially close said end. The outermost plate 26 is made of metal and has a plurality of holes 27 7 through it and the innermost plate} 25 is made of paper or some equivalent material which extends over and closes said holes 27. Said plates, at the ends of the body, serve to hold the filling which is contained in the boov from falling out. The filling may be ground set plaster-of-Paris or asbestos or both, or any other well-known arc-checking substance or substances, but means must be provided at the ends of the body to keep such form of filling from falling out.

The terminals at each end of the fusecase are made substantially alike and are extended through center holes in the endplates, and, as here shown, they each comprise an external portion or blade for connection with a pair of spring-clips or other means for establishing a circuit connection, and an internal portion for connection with the fusible-element. The construction of said terminals forms one of the features of this invention, and, as here shown, their external portions 30 are made flat and rectangular in cross-section, forming a bladelike portion, and said blade-like portions are extended through elongated openings 40 in the end-plates 25, 26, and their internal portions 31 are made cylindrical and formed with sockets 32 extended from their ends inward for a considerable depth, said sockets being designed to receive the endconnectors or plugs on the fusible-element, and, as shown in Figs. 2 and 5, said sockets are screw-threaded for the engagement therewith of said plugs, and, in case they are screw-threaded it is preferred that the threads of the two sockets shall be cut, respectively, right and left. Each terminal has holes 33 in its side-walls which are oppositely disposed to admit of a pin 34 being extended therethrough, and through the adjacent thimbles and side wall of the body of the fuse-case, thereby securely holding the terminal in place. In the manufacture of said terminals they are or may be each composed of a short piece of metal tubing, one end of which is subjected to severe pressure to form the flat blade-like external portion, the remainingportion being left in its original cylindrical form.

The fusible-element which is detachably connected with the terminals and hence may be renewable from time to time, as oocasion may require, forms another feature of this invention, and, as here shown, consists of a strip 50 of zinc or other fusible metal which may be selected, having due'regard to the requirements of the fuse as to voltage and amperage, and two plugs 51, 51 secured respectively by solder or other means, to its opposite ends. Said strip 50 is of any desired shape and dimensions. Said plugs are designed to enter the sockets 32 in the'terminals and preferably arescrewthreaded for engagement therewith, and in case said sockets are formed with right and left threads, then said plugs will be correspondingly rovided with right and left threads. Said plugs are formed with hex-' together with their associated endlates and terminals, and the parts reassemb ed with a new fusible-element. The renewable, fusible-element here shown is simple and may be easily connected with the terminals by a rotary motion of one with respect to the other, and the socketed terminals are very unlike the ordinary binding-posts and other well-known forms of electrical connectingdevices, hence the use of substitute forms of fusible-elements, will not be suggested as convenient.

As a modified form of the invention reference may be had to Fig. 8 wherein the socket 32 in the end-portion of the terminal is made without screw-threads and is slightly tapered, and the plug 51 on the fusible-element is likewise made without screwthreads and is slightly ta red to fit the tapered socket. The taper portion should be shaped so as not to receive readily a fusible portion not intended for it. A ta ring pin 55 is driven through the sockete portion of the terminal and the plug, thereby to detachably connect them together, and in case the plug is made quite long, so as to wrench for extend into the path of the pin 34, its endportion may be provided with a groove to receive said pin.

I claim e 1. An inclosed electric-fuse comprising a fuse-case having removable sheet metal endcaps, terminals arranged at the ends of the case having external flat blade-like portions and internal cylindrical socketed portions, means for detachably securing said terminals to the fuse-case, and a detachable integral unitary fusible-element composed of the flat metallic fuse-strip and cylindrical plugs secured to its ends which plugs enter the sockets of the terminals and are secured thereto.

2. An inclosed electric-fuse comprising a fuse-case having removable sheet metal endcaps, terminals arranged at the ends of the case consisting of tubes flattened at one end to form blade-like portions, the other ends of said tubes having cylindrical socketed portions, the former being arranged externally and the latter internally with respect to the case, and a detachable fusibleelement having plugs secured to its ends which enter the sockets of the terminals and are secured thereto.

3. An inclosed electric-fuse comprising a tubular body having transverse recesses in its ends, thimbles arranged in the open ends thereof, each thimble having a circumferential flange abutting against the end of the body, and each flange having notches made shorter than the recesses in the body, and arranged opposite an end-portion of said recesses, thereby to form bayonet-slots, endcaps arranged on the body and inclosing the thimble and having pins adapted to enter said bayonet-slots, said end-caps having center holes, end-plates interposed between the ends of the thimbles and the end-caps, terminals at the ends of the case projecting through the end-plates and end-caps and a fusible-element arranged within the case having plugs at its ends for detachable connection with said terminals.

4. An inclosed electric-fuse comprising a tubular body having transverserecesscs in its ends, thimbles arranged in the open ends thereof, each thimble having a circumferential flange abutting against the end of the body, and each flange having notches made shorter than the recesses in the body, and arranged opposite an end-portion of said recesses, thereby to form bayonet-slots, endcaps arranged on the body and inclosing the thimbles and having pins adapted to enter said bayonet-slots, terminals at the ends of the case having blade-like portions projecting through the end caps and engaging-portions arranged within the case adapted for engagement with a fusible element, and an integral unitary fusible element arranged within the case and detachably engaging said engaging-portions.

In testimony whereof, we have signed our names to this specification, in the presence of two subscribin witnesses.

LEO ARD B. BUCHANAN. FRANKLIN N. CONANT. Witnesses:

H. B. Davis, 0. DOYLE. 

